Grinding apparatus

ABSTRACT

Grinding apparatus with grinding discs in opposed relationship and forming between themselves a grinding space, one of the grinding discs being constituted of two concentrically arranged annular holder members for disc grinding elements, the inner one of which is axially adjustable relative to the outer one so as to compensate for the non-uniform wear on the grinding surfaces of the disc elements.

United States Patent Reinhall GRINDING APPARATUS [7 2] lnventor: RolfBertil Reinhall, 16

Killingvagen, Lidingo, Sweden [22] Filed: Dec. 12, I969 [21] Appl. No.:884,603

[30] Foreign Application Priority Data Dec. 20, 1968 Sweden ..17634/68[52] US. Cl ..24l/256 [51] Int. Cl ..B02c 7/14 [58] Field of Search..241/256, 259

[ 56] References Cited UNITED STATES PATENTS 1,123,494 1/1915 Craig..24l/256 if el 1 1 Aug. 15, 1972 3,371,873 3/1968 Thomas ..241/256 X1,835,984 12/1931 Haskell ..241/256 X 3,323,731 6/1967 Asplund et a1..241/256 X Primary Examiner-Granville Y. Custer, Jr. Attorney-Eric Y.Munson [57] ABSTRACT Grinding apparatus with grinding discs in opposedrelationship and forming between themselves a grinding space, one of thegrinding discs being constituted of two concentrically arranged annularholder members for disc grinding elements, the inner one of which isaxially adjustable relative to the outer one so as to compensate for thenon-uniform wear on the grinding surfaces of the disc elements.

3 Claims, 3 Drawing Figures PATENTED 15 I973 3.684.200

sum 3 IF 3 mf bun m GRINDING APPARATUS This invention relates to agrinding apparatus.

More particularly this invention relates to a grinding apparatus withgrinding discs arranged within a casing, of which discs at least one isrotatable and which discs between themselves form a grinding space forthe grinding produce consisting of vegetable or similar material. As arule the grinding discs are constructed so that a gradual disintegrationsuch as defibration and/or raffrnation of the produce passing throughthe grinding interspace is effected. The grinding discs forming part ofthe apparatus are for this purpose subdivided into various grindingzones which are composed of ribs and grooves of mutually differingshapes. It is also known to conduct the grinding process in severalstages between varying separate grinding members cooperating in pairs inorder to attain a desired degree of disintegration of the vegetable ororganic material.

One main object of the invention is to provide a grinding apparatus ofthe type in consideration which renders possible a treatment in two ormore stages of the grinding produce between one and the same pair ofgrinding discs rotating relatively one another. According to one mainfeature of the invention at least the one grinding disc is composed oftwo concentric disc elements of which the inner one is axiallyadjustable relatively to the outer one for compensation of thenonuniform wear on the grinding surfaces of the elements. This wear isgreatest in the inner or primary grinding zone which receives thecoarser grinding produce whereas the produce when entering the outer orsecondary grinding zone already has been subjected to a homogenizationor pre-working. The non-uniform wear has previously rendered necessaryreplacement of the entire grinding assembly due to wear in the innerzone only, since otherwise the less effective primary grinding in thiszone would have an disadvantageous reaction on the treatment in theouter grinding zone.

A further object of the invention is to provide a grinding apparatuswhich renders possible that the outer part of the grinding space can beadjusted with precision to a predetermined width, which often is sosmall as 0.02 to 0.03 mms, especially in refiners. The dimensions of thegrinding space in the outer zone can be of the same order of magnitude,as the diameter of the individual cellulose fibers present in thegrinding produce. Then it is essential that the outer grinding zone isformed of disc elements which are fixed stationary so that they retain afully controllable position.

Further objects and advantages of the invention will become apparentfrom the following description considered in connection with theaccompanying drawings, which form part of this specification and ofwhich:

FIG. 1 shows a longitudinal sectional view of a portion of a grindingapparatus constructed according to an embodiment of the invention.

FIG. 2 shows a portion of the apparatus in the same section as in FIG.1, but on a greater scale.

FIG. 3 shows a portion of an apparatus according to a modifiedembodiment of the invention.

In the drawings, reference numeral denotes a portion of the rigid standof the grinding apparatus which stand forms a casing and within which ashaft 12 carrying a grinding disc 14 is mounted rotatably. The grindingdisc carries disc elements 16 and 18 arranged concentrically in knownmanner and usually composed of segments. Disposed in the center may be adisc 20 which feeds the grinding produce radially outwards. A stationarygrinding disc is according to the invention composed of twoconcentrically arranged annular holder members 22, 24 for grinding discelements 26 and 28, respectively, which also each of them is composed ofsegments. Formed between said stationary disc elements 26, 28 and therotatable disc elements l6, 18 is a grinding space 30, 31, to which theproduce to be ground is supplied e.g. in the form of chips or fiber pulpthrough a central channel 32. The grinding disc segments are in knownmanner provided with grooves and ribs.

The outer holder member 22 is rigidly secured in the stand 10 by meansof screws 34 equally spaced around the circumference. Formed axially ofthe confronting circumferential surfaces between the two annular holdermembers 22, 24 are radially extending interengaging threads 36 so thatthe inner holder member 24 when being rotated changes its axial locationrelative the outer holder member 22. This rotation may be brought aboute.g. by having the holder member 24 formed with a recess 37 having aninner gear rim 38 which is engaged by a gear wheel 40 which is mountedon a shaft 42 in the stand 10 and which can be rotated by rnears of ahand wheel 44. The gear wheel 40 is locked in desired position by meansof a nut 46.

The thread joint 36 between the outer stationary holder member or statorring 22 and the inner rotatable and axially adjustable holder member orrotor ring 24 is supplied with pressure oil or grease through a conduit48, so that the joint is continuously kept filled with such lubricant.The lubricant is prevented from penetrating out from the thread joint bymeans of sealing devices such as O-rings 50, 52. The thread joint ishere formed with such a thread profile that it can take up axial forcesacting on the inner grinding member.

According to the invention the advantage is attained that the grindingwhich may comprise defibration and/or refining, can be conducted in twostages with grinding spaces 30, 31 independent of one another withrespect to their widths, but within the same pair of mutuallycooperating grinding members. In this connection the secondary grindingspace 31 is adjusted with high precision through adjustment in axialdirection of the rotating grinding member 14 of the grinding apparatusand the disc elements associated therewith. This adjustment isreadjusted in response to the wear on the outer grinding members so thatthe desired degree of defibration or raffination is obtained. The axialadjustment of the rotatable grinding member may be effected by means ofa servomotor in the manner known from e.g. US. Pat. No. 2,891,733. Theinner grinding space 30 within which the primary grinding process takesplace is adjusted independently of the outer grinding space 31determined with high precision, to a considerably greater space width bycontrol of the annular holder member 24 and the disc element 28supported by the same. The greater wear in this inner or primarygrinding zone can in an easy manner be compensated for by adjusting theaxial position of the inner grinding members 24, 28 by means of the handwheel 44. As has become evident from the description hereinbefore, it isof essential importance that the outer grinding ring 26 is firmlyanchored within the stator ring as the width of the space in this waycan be adjusted with high precision for the secondary grind ing stage.According to the invention it is possible to work here with grindingspaces within the diameter for the individual cellulose fibers and less.

The embodiment shown in FIG. 3 differs from the preceding onesubstantially by the annular inner holder member 24 being actuated by aservomotor or a pressure device 54 which has a piston rod 56 which isrigidly secured to the stator ring 24 and carries a piston 58. Saidpiston subdivides the interior space of the servomotor into two chambersto which pressure medium such as oil can be supplied through conduits60, 62 from a pilot valve 64 of a kind known per se. This valve isprovided with a valve body 66 which depending on its axial positiondirects pressure fluid to the pressure device 54 through one or theother of the conduits 60, 64 as is described in the U.S. Pat. No2,971,704, for example. Pressure fluid is fed to the valve 64 through aconduit 68.

A control nut 70 or similar means is screwed on the outer end of thepiston rod 56. This nut cooperates with the valve body 66 in such amanner that when the inner annular holder member 24 due to aninstantaneously occurring overloading emanating from the grindingproduce is pushed to the left according to FIG. 3 from somepredetermined position, the valve body 66 is actuated for supply ofpressure fluid through the conduit 60 to the left-hand side of theservomotor 54, the holder member 24 and the disc element 28 therebybeing subjected to increased pressure and pushed in a direction towardsthe rotating grinding disc 14 until a state of balance has been reachedagain. lf, to the contrary, the predetermined space 30 of the primaryside between the grinding members is decreased below the predeterminedvalue, a superpressure is instead activated through the conduit 62 toact on the right-hand side of the piston 58. By rotating the nut 70 onthe piston rod 56 the desired width of the primary space 30 can beadjusted to any desired value.

The adjusting nut 70 may be graduated so that it indicates variousgrinding interspaces which may come into consideration. A plurality ofservomotors or pressure devices 54 may be arranged around thecircumference of the stator casing and be controlled either individuallyor when coupled together mechanically by means of a roller chain orthrough electrical rotating members, for example.

The servomotor or pressure devices according to FIG. 3 may be replacedby lockable setting screws which enter screw threads formed in thestator and which can be rotated manually or coupled together so, thatthey are actuated simultaneously for adjusting the axial position of theinner stator ring 24, 28. These setting screws may include an attachmentscrew which is entered by screwing into the stator and through which thescrewing in of a fixing built into the stator ring 24 is effected. Thevalve 64 (H6. 3) may be dispensed with, the grinding member 24, 28 witha socalled floating grinding space being kept pressed against thegrinding produce with an adjustable pressure which is transmittedthrough one or several pressure devices 54.

While several embodiments of the invention have been shown anddescribed, it is to be understood that this is for purpose ofillustration only, and that the invention is not to be limited thereby,but its scope is to be determined by the appended claims.

What is claimed is:

l. A grinding apparatus comprising a housing, a pair of grinding discsarranged within said housing and having grinding surfaces thereofconfronting one another, one of said discs being stationary and composedof a plurality of concentrically arranged annular holder members forgrinding disc elements, each composed of segments, the radially outerone of said holder members being rigidly fixed within the housing; theradially inner one of said holder members being mounted on the inner endof a rotatable shaft extending into said housing; said stationary androtatable discs forming a grinding space therebetween for vegetable orsimilar produce to be disintegrated by defibration and refining of thesame, said annular holder members having their confrontingcircumferential surfaces formed with interengagng threads extendingradially outward of said circurnferential surfaces; and means actuableexternally of the housing for adjusting the axial position of theradially inner one of said concentrically arranged annular holdermembers relative to said radially outer one thereof, said threadspermitting said axial adjustment to be made by an unpredeterminedincrement by means of said inter-engaging threads, the axial position ofthe inner one of said concentrically arranged annular holder membersrelative to the fixed position of the concentric outer one of saidholder members to compensate for the greater wear upon said innergrinding disc elements while maintaining the outer disc elements of saidstationary grinding disc firmly anchored to said stationary holdermember.

2. A grinding apparatus as defined in claim 1, wherein a supply conduitfor lubricant extends through the wall of said housing and opens intothe joint between threads on said outer stationary holder member and thethreads on the inner axially adjustable holder member.

3. A grinding apparatus comprising a housing, a pair of grinding discsarranged within said housing and having the grinding surfaces thereofconfronting one another, one of said discs being stationary and composedof a plurality of concentrically arranged annular holder members forgrinding disc elements, each composed of segments, the radially outwardone of said holder members being rigidly fixed within the housing; theradially inner one of said holder members being mounted on the inner endof a rotatable shaft extending into said housing; said stationary androtatable discs forming a grinding space there-between for vegetable orsimilar produce to be disintegrated by defibration and refining of thesame, and means actuable externally of the housing for adjusting theaxial position of the radially inner one of said concentrically arrangedannular holder members relative to said radially outer one thereof tocompensate for the greater wear upon said inner grinding disc elementswhile maintaining the outer disc elements of said stationary grindingdisc finnly anchored to said stationary holder member, said externallyactuable adjusting means comprising a servomotor consisting essentiallyof a housing having a piston connected through conduits and a pilotvalve to a source of pressure fluid.

l l I I II

1. A grinding apparatus comprising a housing, a pair of grinding discsarranged within said housing and having grinding surfaces thereofconfronting one another, one of said discs being stationary and composedof a plurality of concentrically arranged annular holder members forgrinding disc elements, each composed of segments, the radially outerone of said holder members being rigidly fixed within the housing; theradially inner one of said holder members being mounted on the inner endof a rotatable shaft extending into said housing; said stationary androtatable discs forming a grinding space therebetween for vegetable orsimilar produce to be disintegrated by defibration and refining of thesame, said annular holder members having their confrontingcircumfeRential surfaces formed with inter-engaging threads extendingradially outward of said circumferential surfaces; and means actuableexternally of the housing for adjusting the axial position of theradially inner one of said concentrically arranged annular holdermembers relative to said radially outer one thereof, said threadspermitting said axial adjustment to be made by an unpredeterminedincrement by means of said interengaging threads, the axial position ofthe inner one of said concentrically arranged annular holder membersrelative to the fixed position of the concentric outer one of saidholder members to compensate for the greater wear upon said innergrinding disc elements while maintaining the outer disc elements of saidstationary grinding disc firmly anchored to said stationary holdermember.
 2. A grinding apparatus as defined in claim 1, wherein a supplyconduit for lubricant extends through the wall of said housing and opensinto the joint between threads on said outer stationary holder memberand the threads on the inner axially adjustable holder member.
 3. Agrinding apparatus comprising a housing, a pair of grinding discsarranged within said housing and having the grinding surfaces thereofconfronting one another, one of said discs being stationary and composedof a plurality of concentrically arranged annular holder members forgrinding disc elements, each composed of segments, the radially outwardone of said holder members being rigidly fixed within the housing; theradially inner one of said holder members being mounted on the inner endof a rotatable shaft extending into said housing; said stationary androtatable discs forming a grinding space there-between for vegetable orsimilar produce to be disintegrated by defibration and refining of thesame, and means actuable externally of the housing for adjusting theaxial position of the radially inner one of said concentrically arrangedannular holder members relative to said radially outer one thereof tocompensate for the greater wear upon said inner grinding disc elementswhile maintaining the outer disc elements of said stationary grindingdisc firmly anchored to said stationary holder member, said externallyactuable adjusting means comprising a servomotor consisting essentiallyof a housing having a piston connected through conduits and a pilotvalve to a source of pressure fluid.